It's a good thing Mercedes-Benz's compact front-wheel-drive platform is versatile. The foundation for the brand's A-class hatchback, the high-roof B-class, and the U.S.-bound CLA-class, this architecture serves as the basis for Benz's assault on BMW's X1 and Audi's upcoming Q3: the GLA-class, which makes its in-the-metal debut at the 2013 Frankfurt auto show. +